基金This paper is dedicated to Prof. Zhendong You for his outstanding contributions in the teaching and research field of metamorphic geology in China. I am very grateful to Prof. You for his guidance and selfless help in decades of study and work. We thank Prof. Hans-Peter Schertl and two anonymous reviewers for constructive and critical reviews, which greatly improved the manuscript. This research was co-supported by the National Key Research and Development Project of China （No. 2016YFC0600310）, the National Natural Science Foundation of China （Nos. 41230205 and 41602062）, and the China Geological Survey （No. DD20160122）. The final publication is available at Springer via https：//doi.org/10.1007/s12583-018-0852-y.